Contingency management (CM) is highly efficacious for reducing substance use, and recent data suggest that reinforcing attendance at treatment can significantly improve treatment outcomes. Importantly, CM interventions that reinforce attendance are more likely to be adopted clinically than those that reinforce abstinence. Having objective indicators of drinking outcomes, nevertheless, is critical for quantifying the benefits of attendance-based CM treatment in alcohol abusing populations. New technology is now available to gauge alcohol use in patients' natural environments. The Secure Continuous Remote Alcohol Monitor (SCRAMx) continuously monitors alcohol consumption 24 hours a day. As such, it may be ideal for objective evaluation of alcohol consumption during treatment intervention studies, including those that involve CM. In this study, 114 patients participating in community based outpatient treatment programs for alcohol use disorders will wear SCRAMx for a 12-week period. They will be randomized to standard care or standard care plus CM, with reinforcement contingent upon attendance at treatment. We will assess treatment attendance and alcohol use via SCRAMx and self reports. We expect that patients randomized to the CM intervention will remain in treatment longer and show reductions in both SCRAMx assessed and self reported drinking days relative to those randomized to standard care. Long-term follow-up evaluations will examine drinking outcomes for 12 months. We will also estimate net benefits of CM from both the clinic's and society's perspectives, as well as its cost-effectiveness. In addition, we will assess predictors of relapse, focusing on the associations of GABRA2 and nearby GABRG1 genotypes with differential treatment response. Secondary analyses will evaluate the effects of CM on reducing other drug use, psychosocial problems, and HIV risk behaviors, which have been closely linked with alcohol consumption. Results from this study will be important for guiding future research and clinical use of SCRAMx, and paving the way toward integrating CM into clinical practice for the treatment of alcohol use disorders.